matricestikz-matrixtikz-pgf
The TikZ-PGF manual is clear that for the matrix library, the delimiters are parentheses and braces:
Delimiters are parentheses or braces
to the left and right of a formula or
a matrix.
I would like to use brackets as delimiters for a matrix of math nodes. I have tried \left[ and \right] but they do not work.
Is there any way to get brackets as delimiters for a matrix of math nodes?
Thanks.
In general one can use the remember picture option and apply it all pictures, that should be accessible later. Since your pictures are nested and the options are inheritable, it’s sufficient to apply remember picture only to the upper level {tikzpicture}.
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[auto, semithick, remember picture,
block/.style={rectangle, draw,
minimum width=5em, text centered, rounded corners,
minimum height=4em, text width=5em}
]
\matrix[matrix of nodes, row sep = 2em,
nodes={anchor=center}
] (mx2){
% First row:
label1
&
\node{\tikz{
\node[block] (n1) {node1};
\node[block, right=of n1] (n2) {node2};
}};
\\
% Second row:
label2
&
\node{\tikz{
\node[block] (n3) {node 3};
\node[block] (n4) [right=of n3] {node 4};
\node[block] (n5) [right=of n4] {node 5};
}};
\\
};
\draw (n1) -- (n4); % this works
\end{tikzpicture}
\end{document}
Compile twice to get the right result.
Note that I replaced \tikzstyle{block} by block/.style which is the preferred way. See Should \tikzset or \tikzstyle be used to define TikZ styles?.
The operator - has greater depth than the surrounding numerals. As such, the second smallmatrix is "taller" than the first, causing the delimiters to stretch further. The following highlights this somewhat:
\documentclass{article}
\usepackage{mathtools}% http://ctan.org/pkg/mathtools
\setlength{\fboxsep}{-\fboxrule}
\newcommand{\boxit}[1]{\text{\fbox{$#1$}}}
\begin{document}
\[
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{2} \\
\boxit{5} & \boxit{7}
\end{smallmatrix*}\right) \quad {\def\boxit#1{#1}
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{2} \\
\boxit{5} & \boxit{7}
\end{smallmatrix*}\right)} \qquad
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{-1} \\
\boxit{2} & \boxit{3}
\end{smallmatrix*}\right) \quad {\def\boxit#1{#1}
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{-1} \\
\boxit{2} & \boxit{3}
\end{smallmatrix*}\right)}
\]
\end{document}
\boxit puts a bounding box around the element. Note how the elements in the first row of the second smallmatrix are not vertically aligned.
The marginal increase in height is enough to increase the delimiters. This behaviour can be adjusted via setting elements like \delimitershortfall and/or \delimiterfactor. In the following example, I've set \delimitershortfall to 0pt:
\documentclass{article}
\usepackage{mathtools}% http://ctan.org/pkg/mathtools
\setlength{\fboxsep}{-\fboxrule}
\newcommand{\boxit}[1]{\text{\fbox{$#1$}}}
\begin{document}
\setlength{\delimitershortfall}{0pt}
\[
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{2} \\
\boxit{5} & \boxit{7}
\end{smallmatrix*}\right) \quad {\def\boxit#1{#1}
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{2} \\
\boxit{5} & \boxit{7}
\end{smallmatrix*}\right)} \qquad
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{-1} \\
\boxit{2} & \boxit{3}
\end{smallmatrix*}\right) \quad {\def\boxit#1{#1}
\left(\begin{smallmatrix*}[r]
\boxit{1} & \boxit{-1} \\
\boxit{2} & \boxit{3}
\end{smallmatrix*}\right)}
\]
\end{document}
Read some more about these settings in Automatic size adjustment for nested parentheses.
Best Answer
Use
{[}as the argument forleft delimiter, and similar for the right.The matrix was copied directly from the
pgfmanual (section 38.3 Delimiters), only the delimiters changed. The reason you have to put the braces there is, I suspect, that the delimiter specification is placed within a set of brackets, and you therefore have to separate the delimiter brackets from the brackets for the matrix options.